Typically, a seat structure such as a vehicle seat includes a slider that adjusts the front-rear position thereof, as well as a lifter that adjusts the vertical position (height) of a seat cushion. For example, in Patent Literature 1, a link mechanism including a pair of left and right rear link mechanisms and a pair of left and right front link mechanisms is disposed between the cushion frame of a seat cushion and upper rails. When a lever disposed on a side of the seat is operated to input a torque, a rotational force is transmitted to a gear disposed on the cushion frame. The gear rotates by the rotational force to vertically move the cushion frame relative to the upper rails.
On the other hand, the present applicant has proposed a vehicle seat where torsion bars are disposed on one or both of front and rear portions of a cushion frame along the width direction; arms are disposed on the torsion bars at a predetermined distance so as to be supported by the torsion bars; frames are disposed between the arms; and a two-dimensional or three-dimensional net member is disposed on the frames (see Patent Literatures 2, 3).
Also, the present applicant has disclosed a suspension mechanism having a roll absorption function in Patent Literature 4. This roll absorption suspension mechanism is disposed so as to be stacked on an upper portion of a vertical-vibration absorption suspension mechanism.